On-line catalog systems typically allow an end-user to search for a particular item or class of items, and receive results based on the item or class of item searched for. Typically, the results are displayed according to their relevance to the end-user's query. The display may be changed by the end-user according to user-defined criteria. In addition, some on-line catalog systems allow an administrator of the system to modify the display of results and behavior of the system based on additional considerations, such as business considerations. For example, the administrator may choose to promote a particular brand within a class of items searched, by displaying the brand among the top ten results.